Ammunition



www

L. F. BIRKELAND AMMUNITION Dec. 3o, 1947.

Filed Jan 11,/ 1944 Il i :IIIIIIIIIII .r vfff Ailllllf l Leigh Birkelmld r @ma @Mgfjw Patented Dec. 30, 1947 PATENT OFFICE (Granted. under.. aetn'eli. i; 'Theinventionl described-:herein 1r1xay bemann-ik factured and. used by.-ory for, the: Government Vfor.,H

governmental purposesJ Without` the.l payment to.

meof any. .royalty thereon.,

The.A invention relates to, ammunition and urlare ticularly.. tok av projectile.. having, characteristicsadaptingit to use-,Withconventional rweapons and f loading-Apracticel to attain higher,vel.ocities with. consequent atteningm offtheV trajectory. over., dist-, tances suiiicient-tforeffectivecomban Whilesuch attainments .haver importanceirr.all-` calibers for many-situations, theyare particularlyv important in-small arms, andffhavelsuperior yalue'a. inA aerial combat.

The intention in its present embodimenthasl. foran important objectto presenta formadapted to use'in current gun` forms', and utilizing largely. present practice in ammunitionl-manufacture and; preparation for use; shipping and handling from. factory to gun, and enabling fuse-.of familiar ammunition Vbelt` assembly, andl breech and firing.. mechanism of conventional. forms. say, While the projectile is longer, its` exposed part" in a round is apprpxirriately4 conventional in size,V and shape.v In these Yrespects the invention is specially useful in infantrytsmallarms as Well as in Weapons for**aerial*confibat. Itis Well adapted tourskenin Weaponssuchas the 5,9 caliber orhlargerattrait mathriegua @n-,it thpueht Q'f velue in. airptait Cannell.: i

For. aerial CQmbatamierieeemallarles geen telly, the. 10W quadrant .angle df departure and eenerallytiat-treiet Ory enable mint blank. fir ,s Siderable ranges! and. bnsiitrirle the 'slsf' tot leadthe t'atetasie91uiea` The leas;

t cette,

h'Qatteinmtnt. O f.- the.. f-Qrtetine urpose of the inventionl'to i `a entstammtredttteein thafettre energy" needed the bilrninefif., theportdte @ha v That. it t0 creasing the in other factors to a greater factor of energy of translation of the projectile, but'haye further greatly increased this force, by a coordinated modification of the propelling powder, vvithoutin-l stressesrdeveloped in `the barrel of thegun. l l It is av specic aim of the invention to obviateneed for riiiingv in vthe gun and to enable useof a smooth bore, thereby reducing materially the,

; cost of theA weapon and avoiding expense for new* tools in production of the arm; andatrthe same time eliminating a large element of friction and the factor of torqueA energy heretofore expended on the projectile with the,` sacrifice of. velocity., To compensate for this elimination of rotation ,inf thegun, it is a purpose to soconstruct the pro jectil that it Will maintain stability of Hight and a good approximation of alinement of vits axisv With thetrajectory. In effectingfstabilization, I have formed a projectile of greater length for a given mass, with its'centerof gravity further for- Ward, and it is an important attainment of the invention that this projectile and a standard cartridge case are embodied so as to be readily assembled in the conventional clips, bandoliers, maga; zines, and'machine` gun belts, andto function in the `same manner as prior ammunition in breechl and firing mechanisms.

A further purpose isv to reduce head resist-ance of air to the progress ofthe projectile and par` ticularly to eliminate or reduce the zone of airV density at the nose of, the projectile by which it tends to be yawed, and to reduce other elements.v of drag both in ight and in the gun.

It is also a purpose to reduce the Weight ofthe.` projectile in order tor gain still further. velocity," and at the same time enable the benefit of; accreted velocity to. be maintainedover a" satisf-A factory range. A

furtherpurpose is to enable a. further gain of velocitybythense'of a Indre rapidly burning popellinglpowder charge, and, by reason ofithe greatervv acceleration "of the projectile' due to the modication ofl factors bf energy expended, to produce a conventional pressure curve, of barrel length "and pressuremwiththe new powder, not,- Withstandingit's highburning rate. This enabler.`

the nse of conventional proportions in the barrel,-

I `andfurther avoids eiipense in manufacturing' costs.

Another. Objectis to enable the. use of a tubularv Qrojectila'w'ith novel functions in the ring and; flightA operations, and otherwise. At the samel 3 are attained, it is a still further object to utilize therein the standard aircraft machine gun currently used so that it will remain, both in principle and operation identical with the standard type.

It is an important desideratum in this invention to provide for the communication of the propul sive force of the burned charge over a maximum cross sectional area of projectile, so as to most effectively utilize the available accelerative force, limited only by the caliber of the gun, yet during propulsion to substantially reduce the presented area and consequent head resistance and drag as compared to conventional projectiles having an equal effective cross section on ring. That is to say, the flight caliber of the projectile is substantially less than its initial or loading caliber.

Likewise it is sought to lessen the degree of vacuity at the tail of the projectile in flight.

Additional objects, advantages and features of invention reside in the construction arrangement and combination of parts involved in the embodiment of the invention and its practice otherwise as will be understood from the following description and accompanying drawings wherein Figure 1 is a view of a round of ammunition embodying my invention partly in elevation, the projectile and cartridge case being in longitudinal section;

Figure 2 is a similar view of a modiflcation using a solid projectile.

Figure 3 is a rear View of the projectile.

Figure 4 is an enlarged fragmentary longitudinal section of the base of the projectile head and tail.

Figure 5 is a schematic sectional view of a tapered bore gun and a representation of my projectile at successive positions therein on ring.

I am aware that the principles of rocket pro jectiles have been incorporated in ammunition heretofore, but my invention is distinguished from these prior efforts in several important respects, as Will appear.

There is illustrated a round of ammunition comprising a cartridge case I0, which may be produced as usual in a conventional form as heretofore and in a size proportionate to the caliber and construction of the gun in which it is to be used. It may be loaded and primed conventionally (the primer n-ot being shown), except that the propelling charge II may be of a faster burning quality than usual for a cartridge of a given size and conventional projectile. While I have contemplated using my invention in guns constructed as those now used in the smaller calibers, except for omission of rifling, still, my invention is specially advantageous for use in smooth tapered bore guns, and my cartridge is suggestively shown tapered, although it may conform to other standard shapes heretofore used.

Due to the fact that no change in known gun structure is contemplated, excluding the omission of rifling, I have not illustrated the gun in detail. The case I is formed with the usual forward reduced neck I2, heretofore adapted to enter into the bore of the gun behind the riiling and the rearward enlarged chamber-fitting part I3, a joining conical shoulder part I4 intervening.

The projectile may be solid as in Figure 2, and of a weight corresponding to that of the conventional bullets heretofore used in weapons of the same caliber, but in Figure l, I have shown the projectile I much lighter by reason of imparting thereto a tubular form, in order to attain all of the advantages and objects heretofore stated, as well as others which will be manifest.

In Figure 1 the projectile consists of a bullet head I6, the length of which corresponds to that of the conventional bullet, but instead of having a pointed nose, has a broadened nose I'I of annular form terminating in a plane at right angles to the axis of the projectile, the ogival curve I8 yterminating forwardly immediately at this annular nose, and having a radius of approximately ten calibers, as shown, although this may be varied to accordance with current practice, or otherwise for special performance characteristics found practicable with my invention. A coaxial cylindrical bore or passage I9 is formed longitudinally entirely through the head I6, the diameter of which is but slightly less than the maximum external diameter of the nose I1, depending on how sharp an edge 2U it is desired to form on the annular termination of the nose. The diameter of the passage may be determined also in ac-l cordance with formulae'based onY desired flight characteristics including mass deceleration and avoidance of yawing. It is thought practicable in some aspects to remove material approaching seventy percent of the caliber in forming the passage I9. As illustrated, the proportionate measurement in relation to the caliber and length of the head is not intended as estimated or arbitrary, and will be largely affected by the most practical approximation of an ideal curve of deceleration of flight in the desired effective range of the projectile wherein the objects ilrst set forthor the more essential ones-are approximated.

The body or head terminates rearwardly at and' with an annular thick interior base shoulder 2|, in the present instance finished in a transverse plane, midway of the length of the reduced part I2 of the cartridge case I0, an integral thickened cylindrical rear wall 22 being continued rearwardly from the shoulder 2|, the outerface of which is flush with the adjacent external face of the head I6. It extends as far as the junction of the neck and conical parts I2 and I4.

From the thick wall part 22, the material of the head is continued rearwardly with the same internal diameter, but slightly relieved on its external face, as at 23, forming a cylinder, or tubular tail 24 the length of which in this instance is sumcient to project into the cartridge case half the length of the latter, terminating in a plane normal to the axis of the projectile. The wall of the tail from the part 22 is of uniform thickness as shown but may be diminished in thickness toward its extremity, dependent on the refractory quality of the material therein, such tapering, if any, is preferably effected by diminishing the material at the inner side but maintaining a uniform external diameter.

A shoulder 25 defines the forward limit or boundary of the relieved part 23, but its radiall altitude may be much less than shown, and it is believed that the difference may in eiect be,

produced by the electrodeposition or other application of a face coating 26 (Figure 4) of a metal of low friction characteristics in engaging the face of a smooth-bore barrel, such as copper, tin, or other suitable metal or alloy. In the event that the projectile is used in a, materially.

may be formed of steel or other approved hardv atenerse-4e.,

5?; taught metal?. for,` airplaneiuse; but therma'jorr parti oftlie. head; may-f be of-"jscme: otherL metal,-v in: ace cordance with approvedi practices,- jacl'reted;` steel ory other.` metal', theljacletE4 materialV prefers ably' continued? rearwardly` to frin the tailj Z4. The material of the head mayfalswbespeciallyj adaptedv toV progress-ive caliberA reduction inV thegun, as'will4 bedescribed.

The mouth-of. the cartridge case is set into the peripheral-cannelure of the body I'as customaryheretofore, and i-ndicated'at 211. l

Set separablyf against the shoulderT 2I, within-i the rear wall 2-2,` there-isapseudoo-bturator,l cap or stopper 2'8 without expansive qualit-y, however, and intendedto remain v loosely .setagainstthe shoulder'v 2'I` but' pressed` tightlyftherea'gainst by the expanding gasesl inthe cartridge andbarrel during' propulsion of the projectile. The inner part-29- ofv this cap is semispl'lericalA or arched to withstandA pressures within the-cartridge' case, and is-` of less diameter than the interior" of the wall; 22, so as to afford a; materialL clearance there'- around', While at theouter side ofthe stopper' a boss'SIl is integrall'yformedfthereon; loosely'iittedfin the endof the passa-ge" ISf This'stopp'er may hel formed of" a suitable metal, or mayb-e` made. of a combustible or otherwiseI expendable material. In the first instance it" will be cleared rearwardly" from' the projectile soon after leaving' the'.

gun, and inthe second instance it may' burn in;

part while in the' gun and its combustion com'- pleted soon" after. I'n one case the cap will be bodily' expelled rearwardly by air rushing throughH the passage I9, or, inthe other case,l theV remnants similarly expelled. In each. instance, the cap functions asa transient. closure device.A The intermediate exteri'or portion SI ofthe body ofi the projectile may be termed the bourrelet but contrary to conventional practice, is off a diameter corresponding; tozthat of the bore ofi a riedf gun at the bottoms. of' the grooves ofthe rifling, instead of' the lesser diameter involved at theu tops of the lands.L Also, contrary to conventional practice no'clearance is contemplated between the bourreletand the smoothbore, althoughif desired there may be a slight relief or modification of diameter at partsofl the periphery of thehead I'I to lessen the amount of material to be displaced in the entry andmovement ofthe projectile through the barrel;k This would involvesuch slight differences in conventional; barrel formsfV that they may be produced'by varying the amount of material applied.' or` deposited on the exterior, of the head or bodyoff the projectile, at different parts.

In the case.- o asteel body It-.iti may be found desirable to soY proportion the applied. material that displacementV ofv material' in the barrel will.Y occur entirely in the applied material', avoiding higher stresses, on the. barrel whichmight de-` velop vif the steel body should require resizcilciziontapasa,

Operation;

I'rr the use of'my invention as described';,a: gun having: been provided with a smooth bore. (which would enable-a simpleand' economical renewal of life of a wornriedtubel, my ammunition prepared as, described may be. introduced or fed to; the, breech mechanism conventionally and'. 'red usual. Upon det'onation, the. powder having thenew characteristics described and lling the cartridge including the space within and surrounding the holl-ow tail, burns quickly, the projectile moving forward and a small displacement 6?v the: applied* lbw'rfictionematerial 233occurring@ ais eiproje'ctile: enters-ftlieslcvarrelv 'Ifhereafter.n tl'ie projectilemoves* with1 negligible impedance.x tiiroug-hf-tlie1barrel'fwith'rthe heightened accelera tinfheretofre.-indicated In ther-burning! of the. powder4 contained"` in 1 thee-Y tail` portion; anyex-pansive' forcesltending to en-N large'theidiametenofithe tail is 4opposed andpres' su-r'es equalized;ahy-'propagation ofi ignition inthe-- space betweenf the tail? andi wall ofi the cartridge case, and by translativeemovementfofgasesefionr thelargerbodyl ofTex-plosive rearwardlyiofthe tail. The' tailthusretainslitsecylindrical form andsizer-l as-it movesi from the-` cartridge.- Incident to the? passage lofftlie` projectile-through a conventional` slfiapeof barrelf having but slight if anytapeif, therel Willii remainy a1 clearance between:4 the tail' an'dwall ofth'e =bore by which the sustained pres--y sures aresequalized': within and' withoutA the tail; so' that nolfictionalengagement between'- the -t'aill and -barrel'occurs- Upon leaving* thegun, after theY pressureof propelling` gaseshas= diminished sufficiently, theeC air"compressed?into-tl'ief-passage- I9; by itspresal sure'- and" inertia; and? that@ progressively: pene=- trate'dl wi-ll press =the -cap'28firearwardly vfrom thez projectile, due -toithegreaterlmass ofthe -projectile1 andthe relatively greater area ofthe'cap' exposed;y tothe air from-the passage I 9.

Slioul'd aicap-ZB ofi combustibleor Votherwise ex; pendiblemateriali be' used it'sf greater central' thicknesslby reason of="its=semispherical rear facer willi delay# combustion'v or collapse suciently forE it'i to transmit the propulsiveA forces adequatelyuntila'f-terthe projectile leaves the barrel; after-A which par-tic'sles'- remaining willi be ejected: reare wardly from the projectile as in the: caseof the metal orfnorr-combustible caps;

A'sI soon asthecapVA 2-8 i'sL cleared, air passesf through the-passagev I9VT in substantial quantity; due in parti-toi arcompr-essionthereof"iinmediatelyfr at'then'os'e -ofthe-proj-ectile-aswell as t'o relativel translative movement oftheA proj ectile and inertia ofthe ai'r; This largely relieves the vacuous con-- ditionwhich tends tod'evelop immediately behind? the/projectile; andfin; conventionalprojectiles be-u cornes-a material factor 4of-"decelerati'onl In,v addi` tion, the head resistanceandi ii'npedancefis diaminislied, and" also the small areaY of dense air fbrm'elillv in4V advance: ofi tlie= nose of ordinary pro--v jectiles iszrelieved; so'that yaW-ing i'orcesinciden-tl thereto' are largely,` if"notenti`rely eliminated; In thesfurther Hight of the projectile the center of? gravityb'einglocated nearer the' nose than thevl extremityof the tail', any: tendencies of the pro-- ject'iletoyaw will" be corrected by: resultants ofZ air forces acting on the tail, and the axis ofthepr'ojectifle' willc beY maintained in a close approxi-'matiorr ofalinement `with the direction of flight;

catedl somewhat' further to the rearl than the-V Shoulder.r 2|-,- wliile-the rearward' wall' 22', corre-i sponding to'l theone 252E beforedescribed', is of1 similar thickness; though shorter, since itv stops; at the conical part I4 of the case I0. The tail 24 is of the same shape diameter and length as that first described with a corresponding relieved outer surface. I have contemplated a further method of producing a reduction of head resistance in the projectile after obtaining the initial advantage of exposing a much larger transverse area to the propulsive forces of the barrel powder charge, and in Figure 5, I have shown schematically an exemplication of the use of my projectile in a suitable structural quality in a pronouncedly tapered gun bore.

In this instance a formal representation of a gun barrel or tube 35 is shown, the length of which is shortened for the purpose of illustration, although it maybe of the same or a different relative length. The bore 36 is smooth and circular in cross section and is progressively reduced in diameter from the chamber 31 to the muzzle. The total reduction in diameter of the bore is proportionate to a predetermined fraction of the inner diameter of the passage I9 inthe head I5.

The material of the projectile is in this instance preferably readily compressible under forward progression in the bore with a moderate expenditure of energy of propulsion to overcome the Q additional friction and the internal resistance of the material of the projectile to such deformation. The projectile may otherwise be of the same form as before described (except that the ogival curve may be of materially shortened radius) and with the same elements as described in reference to Figure l herein. 'Ihe stopper cap 38 if non-combustible should not exceed in diameter the minimum interior diameter of the tail after constriction and at its forward side is preferably conical, with low altitude of its conical elements.

In the use of the modified construction, a slower burning charge may be found more desirable than that used in the bore of conventional proportions, as may be determined by experiment and calculations familiar in interior ballistics.

Upon firing a round according with the modication last described, the equalization of pressures occurs as iirst described, within and without the tail, but in the event that the smaller diameter of the bore is less than that of the tail the latter` will finally be engaged and compressed to the smaller diameter.

As the projectile progresses from the chamber position a, Figure 5, forwardly, it is compressed to a smaller diameter as at b, the passage I9 being correspondingly narrowed, until, when the projectile leaves the gun,A the passage is quite small. If not closed, it may still function in flight to relieve the air density at the nose of the bullet, and also in part lessen the vacuity at the tail.

The whole projectile having passed from the gun it will have a cylindrical form in the reduced diameter, substantially as at c, Figure 5, and if the ogival curve has been sufficiently shortened the nose will also be considerably reduced. There may be a slight flaring of the forward part of the passage I9 due to lack of compressive action atthe very tip of the nose.

In the movement of the tail portion through the barrel, by the selection of appropriate material, and due to the rapid heating of the entire cross section of the wall of the tail as well as the fact that finally practically all pressure acting on the tail Will be from Within, it will be firmly pressed against the wall surfaces of the bore as at b, Figure 5, and kept in a symmetrical circular contour while being reformed to the smaller' size. The projectile will lbe relativelymore elongated in relation to its transverse dimension, if not actually elongated, and Will thus. approach more an ideal shape in relation to mass, for sustained ilight at high velocity. By the use of the stopper with conical face against the shoulder 2l, as the projectile becomes reduced in diameter the edges of the shoulder slide on` they conical surface of the stopper, pressing it rearwardly and having it free at all times to be pushed rearwardly by air pressure acting through the passage I9 against lesser pressure at the rear.

While I have disclosed my invention with particularity in the best forms known to me, it will nevertheless be understood that these are purely exemplary and that modifications in the construction, arrange-ment, and combination of parts, substitution of materials and substitution of equivalents mechanically and otherwise, may be made without departing from the spirit of the invention, except as it may be more particularly limited in the appended claims wherein I claim:

1. A projectile consisting of a full caliber head portion having therein the major component of mass of the projectile and adapted for propulsion through a gun barrel and the like, said head having a longitudinal passage open entirely therethrough, a closure for the rear end of the passagefreely displaceable rearwardly, and a tubular tail formed integrally on the projectile and being of less caliberal measurement than the projectile but larger interior diameter than saidv passage, for free movement of the closure therethrough,

2. A round of ammunition comprising a conventional cartridge case having forward neck portion and a rear chamber portion, a projectile consisting of a full caliber head portion approximating standard length having therein the major component of mass of the projectile and having an integral thin walled cylindrical tubular tail of less diameter, the projectile head being set in the neck of the case and extended forwardly therefrom conventionally, said tail extending concentrically into the chamber portion of the case, an axial air passage of less dia-meter than the tail being formed through thehead, a charge of propellant in the case and within and around said tail and a loose expendable closure member of less diameter than the interior diameter of the tail arranged in the tail and set against the head at the end of the passage.

3. The structure of claim 2 in which said closure is of combustible material.

LEIGH FORSTNER BIRKELAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 53,582 De Goursey Apr. 3, 1866 517,560 Ashleyv Apr. 3, 1894 590,428 Bennett Sept. 21, 1897 1,141,042 Davis May 25, 1915 1,669,969 Caruth May 15, 1928 FOREIGN PATENTS Number Country Date v1,033 Great Britain Apr. 28, 1853 19,912 Great Britain Oct. 23, 1893 427,714 France June 2, 1911 

